Cam Ward hit a 3 with 5:43 to cap a 21-8 run and push Vermont's lead to 77-60.
Vermont (10-8, 2-1 American East) raced to a 28-11 lead when Everett Duncan hit back-to-back 3s with 11 minutes to play before halftime. But the Hawks proceeded to outscore Vermont 31-11 and took a 42-39 lead to intermission.
The lead was short lived as Ward came out of the break to hit a 3 to tie it, and Nate Rohrer's layup gave the Catamounts the lead for good.
Pancake Thomas led Hartford (6-12, 1-2) with 29 points on 10-for-21 shooting from the field. He was 4 for 8 from 3-point range and 5 for 8 from the free-throw line.
The Catamounts held a 40-23 rebounding edge.